In the administering and/or withdrawal of fluids from a patient, an access port is often used comprising a reservoir having on one end a self-sealing septum through which a needle is insertable. The reservoir further comprises an exit passage fluidly connected to a cannula. After surgically implanting the access port in the patient such that the septum is positioned subcutaneously, and attaching the other end of the cannula to a catheter inserted into an internal part of the body (typically a vein), fluids can be administered and/or blood samples taken through the insertion of a (typically non-coring) needle into the reservoir via the septum. Thus in the case of administering a fluid, said fluid flows through the needle, into the access port and through the attached cannula. In this way repeated access to the inside of patient is facilitated. In conventional access ports the reservoir may be made from metal or plastic.
When the needle is inserted through the septum, the resistance is quite high (around 8 N). In order for a medical professional to ensure that the needle has completely traversed the septum, allowing the needle bevel opening to be exposed beneath the septum, he or she must feel that the needle is touching the base of the reservoir of the port. This requires that he/she feels that the needle can no longer advance. If the internal base of the reservoir is made from a soft material, the needle will mark the internal base of the reservoir.
Access ports having a plastic reservoir and metal base are known from prior art.
For example an access port is known from U.S. Pat. No. 6,527,754 B1 comprising a housing made from molded plastic, an exit passage and a septum. The internal base of the housing is formed from a metallic shielding plate having a bent rim portion, which is molded or bonded to the housing. The metallic shielding plate, housing and septum define a reservoir.
In the access port according to U.S. Pat. No. 6,527,754 B1, the metallic shielding plate is fixed to the housing only at the rim portion. The shielding plate can come loose from the housing due to the forces that result from repeated needle insertions and other forces during operation. In other words the retention of the metallic shielding plate can be compromised which can lead to loss of sealing between the housing and shielding plate, and in the worst case detachment of the metallic shielding plate from the housing. Therefore it is a problem in the case of ports having a plastic housing and metal shielding plate that the shielding plate does not remain leak free or even can come loose from the housing.